The Silver and Orange lines end the eastbound trip at the Eastern Market station during phase 2 of SafeTrack on Monday June 20, 2016. (Mark Miller/The Washington Post)

Metro’s long-term subway maintenance effort, which so far has caused disruptions almost exclusively for daily commuters, is about to also have a big impact on visitors to the Washington region, with two weeks of rail-line shutdowns near Reagan National Airport.

For seven days starting Tuesday, no trains will run between the Braddock Road and National Airport stations on the Blue and Yellow lines, although both stations will remain open. Then, from July 12 to July 18, train service will be halted between the airport and the Pentagon City station, meaning the Crystal City station will be closed.

For travelers using National, the next two phases of Metro’s nearly year-long SafeTrack subway overhaul will mean no rail access to or from the airport, first in one direction and then in the other, for much of July.

It’s unclear how many airport patrons will be impacted by the disruption. But last year, close to 2 million travelers passed through National in July, according to the Metropolitan Washington Airports Authority. And so far this year, compared with 2015, passenger traffic at the airport is up almost 2 percent, MWAA said.

About 20 percent of travelers who arrive at National to begin their jet trips use Metro to get to the airport, officials said.

“Make no doubt about it, this is going to impact all passengers coming in and out of Reagan National, regardless of whether they rely upon WMATA and the Metro system for access to the airport,” said Margaret McKeough, chief operating officer for MWAA.“We’re having record passenger activity levels at Reagan National this year that have already provided a taxing situation for our roadway system as well as all of our modes of transportation. . .please plan ahead, and plan wisely.”

In addition to inconveniencing travelers at National, the July track-repair work near the airport — like two SafeTrack projects elsewhere in the system this month — will cause headaches for tens of thousands of Washington-area residents who use Metro every workday.

For a week starting Tuesday, riders headed north on Blue and Yellow line trains that originate at the Franconia-Springfield or Huntington stations will have to get off at Braddock Road. From there, shuttle buses will carry passengers to the airport station, where they can reboard the subway and continue their trips.

Meanwhile, trains headed south on the Blue and Yellow lines will terminate at the airport, with shuttles ferrying riders to the Braddock Road station.

Metro said train service south of the Pentagon station will be reduced by about 50 percent during the week-long project, disrupting an estimated 50,000 passenger-trips each weekday.

“We’re calling on all Blue and Yellow line riders in this area to avoid the Metro where possible,” said Metro General Manager Paul J. Wiedefeld. “Telecommute, bike, carshare, slug, whatever you can do to reduce the strain on the system and to make your ride a little smoother.”

The same sort of disruption and shuttle system is set for the Blue and Yellow lines north of the airport for a week beginning July 12, with buses carrying passengers back and forth between the airport and Pentagon City stations. Adding to the aggravation, the Crystal City station, located between the airport and Pentagon City, will be closed.

This project, which will also reduce service by about 50 percent south of the Pentagon station, is expected to disrupt about 86,000 passenger-trips per weekday. During the July 12-to-July 18 project, there will be no Yellow Line rush-plus service, in which Yellow Line trains leave from both the Huntington and Franconia-Springfield stations at certain times.

The two shutdowns near National are the third and fourth of 15 scheduled maintenance projects, or “surges,” in the SafeTrack program. The projects, involving major infrastructure upgrades, are part of Metro’s effort to revitalize and improve safety in the 40-year-old, failure-prone subway system after decades of maintenance neglect.

MWAA spokesman Chris Paolino said officials at National are bracing for confusion, especially among out-of-towners arriving at the airport who know nothing about Metro’s massive maintenance program.

“The first thing we’ll do is make sure we communicate as much as possible with passengers while they’re in the airport, so they understand that there are other forms of transportation that are available,” he said.

“There will be announcements. There will be signage. We’ll have an alert on our website,” he said. “Our ground-transportation page will have a section specifically about [SafeTrack] that will direct people on what they can do. And our Travelers Aid people will be up to speed and ready to help. We’re trying to do every form of communication we can think of.”

Cab lines are expected to be longer than normal, he said. But officials hope that more taxis will be available, so that wait times will not be excessive. In Alexandria, officials this week approved a $15 flat fare for trips between National and three Yellow Line stations: Braddock Road, King Street-Old Town and Eisenhower Avenue.

To augment Metro’s shuttle buses, Paolino said, “we’re working with the taxi companies, with Uber and Lyft and everyone to make sure there’s as large a supply of those vehicles as possible for people who choose to use them.”

And it won’t be just air travelers looking for ground transportation. Of the 12,000 people who work at National, about 700 typically commute on Metro, officials said.

Earlier this month, before an ongoing rail-line shutdown on the eastern side of the subway system, Metro warned that shuttle buses would be able to accommodate only about 30 percent of the tens of thousands of commuters who typically use that part of the system during rush hours.

The transit agency issued the same caution concerning the shutdowns near National, saying that shuttles will be exceedingly crowded, with long waits, unless about 70 percent of rush-hour commuters who normally use that part of the system either work from home or find other ways of getting to and from their workplaces.

Officials on Tuesday warned passengers to consider alternatives, including supplementary bus service, hotel shuttles, taxicabs, ride-hailing services and bike sharing.

The alternatives will include free and more frequent weekday service on Metroway, the bus rapid transit service running between Braddock Road and Pentagon City; free and more frequent DASH bus service on two routes — the AT3 and AT4 — which operate between Alexandria and the Pentagon Metro station; and more frequent service on the 11Y and 10A Metrobuses, which ferry passengers between Mount Vernon and Potomac Park in the District, and the Huntington and Pentagon Metro stations, respectively.

“We urge all citizens to rethink your commute and try alternate travel options as WMATA works to improve safety along the Blue and Yellow lines,” said Alexandria Mayor Allison Silberberg. “Consider walking, biking, taking a bus, carpooling or telecommuting or taking the [Virginia Railway Express].”

The first SafeTrack project, from June 4 to June 16, caused service delays on the Orange and Silver lines, mainly in Virginia, where trains traveling in both directions were forced to share one track between the East Falls Church and Ballston Metro stations.

But that single-tracking on the subway’s western side was a relatively small aggravation compared with the disruption riders are now experiencing, centered on the system’s eastern side. Since June 18, rail service has been halted from the Eastern Market station, on the Orange, Silver and Blue lines, to the Orange Line’s Minnesota Avenue station and to the Benning Road station on the Silver and Blue lines.

That project, which is due to conclude Sunday, has caused a ripple effect of delays and crowding elsewhere in the rail system, with trains running less frequently on the Orange and Silver lines. Meanwhile, to ease train traffic in downtown Washington, the Blue Line has been operating only in Virginia and only on a reduced schedule.

However, Metro said, because many thousands of riders in eastern part of the system have heeded the agency’s advice to avoid the subway, crowding and delays have been manageable and shuttle buses have been able to operate relatively efficiently. Ridership dropped about 75 percent in the area of the shutdown.

Metro officials hope to have the same good fortune near the airport.

“What people have done is they’re planning ahead,” Wiedefeld said. “They’re making arrangements. Whether it’s bus, whether it’s Uber, whether it’s carpool, whatever it is. That’s what we’ve seen in the first two surges, so I would expect the same to play out. Particularly on air travel ... people do plan pretty far ahead on those types of trips, so I think they’ll be in good shape.”